Rammed earth, sod, yak wool, reclaimed wood, oriented-strand board, straw ... nowadays, the smorgasbord of offerings in alternative building methods and materials is staggeringly abundant, if not a little confusing.

On the one hand, you've got architectural innovators advocating prefabrication to make a better "housetrap." With high-tech products and cutting-edge mass production, they are trying to develop a new housing methodology: designerly, affordable, energy-efficient houses built to withstand anything, come hell or high water. On the other hand, there are the ecological purists who have turned to older methods of shelter building. They embrace sustainable resources like straw and dirt, making homes as natural as a footprint in the sand.

The problem with the prefab movement is that it, like most new construction, typically uses less-than-sustainable resources, like steel and wood. (True factory production could indeed reduce our ecological footprint by eliminating the waste typical of construction, but that's still quite far from reality.) And the problem with environmentally sound but old-fashioned building techniques is that they require too much time and skilled labor to solve our society's need for affordable green housing on a grand scale.

So where is an eco-friendly homeowner or builder to turn?

In this era of scouring the earth for the magic bullet in home building, few ideas can compete with the weird, pragmatic beauty of the used shipping container. Cheap, strong and easily transportable by boat, truck or train, these big steel structures now litter the ports of America as mementos of our Asian-trade imbalance. (Many more full containers arrive on our shores than depart, so ports either ship them back empty -- to the tune of about $900 per -- or sell them.)

Hurricane proof, flood proof, fire proof, these metal Lego blocks are tough enough to be stacked 12-high empty -- and thus can be used in smaller multistory buildings. Used containers (which can be picked up for $1,500 to $2,000) often have teak floors and sometimes are insulated. The bright orange, blue and rust corrugated boxes may not appeal to everyone. But contemporary hipsters find them not just the ultimate in postmodern appropriation but aesthetically pleasing as well.

And even though containers have little of the crunchy nostalgia of the hay-bale house or the yurt, they trump most other forms of green building because, in the current economy, they are virtually a waste product. Making a building (which can last and last) out of what is essentially a huge piece of industrial detritus takes recycling to a new level.

The concept of using shipping containers as buildings is hardly new -- institutions like the military have been using the structures as temporary offices, bunk houses and showers for some time. Examples of designers incorporating shipping containers into residential designs date back to 1982.

But in the past couple of years, a field known as container architecture has evolved, offering the hope that what was once only a post-industrial pipe dream can emerge as a practical new building form. A handful of architectural firms around the world -- from New York to New Zealand -- have built prototypes or plans for shipping-container homes. Most of these designers develop each house or project as a one-off, but one prefab factory has begun pumping out little container homes that are not meant for the military encampment or the disaster relief camp. Rather, they are meant for the discerning homeowner avid for something new.

Since his New Jersey factory went into production this year, Adam Kalkin has sold a dozen of his so-called Quik Houses, each based on five shipping containers. These are two-story, 2,000-square-foot homes with skylights and enormous glass windows, equipped with three bedrooms and two baths. The price, which ranges from $76,000 for the basic kit to $160,000 (with all the bells and whistles like a stainless-steel kitchen and mahogany doors), is under $100 per square foot, not including land or foundation.

Kalkin, a celebrated young architect and artist, has made a name for himself by walking a tightrope between the straight-laced world of architecture and the mad land of performance art. His recent creation -- the "Push Button House" -- is an art installation of a "home" built inside a shipping container with mechanized walls that open like a blossoming flower. His Web site, which promotes his prefab container homes and books, also sells kitschy homemade candy ("classic candy melange") and offers a pay-per-minute phone line for your confessions.

Among the custom amenities in the Quik House promotional pamphlet is a $1,000 dinner prepared by the architect in the client's new home. Kalkin also delves into humanitarian work, including a collaboration with fashion model Natalia Vodianova on a series of container-based recreational centers for underprivileged kids in her native Russia.

Given his orientation as an artist-inventor -- not a conventional architect, much less a businessman -- Kalkin is a little dismissive when it comes to discussing his place in a movement that he characterizes as "very ideological."

He says he never imagined himself running a construction factory at the forefront of a new building form. "I just like the found-object quality of these things. It wasn't a rational proposition," he said, adding that he is developing houses made of fabrics and other materials that he declines to mention. "I'm not really part of the movement."

Rational or not, his work is in the vanguard of a building form that is gaining mainstream interest and acclaim. Recently, architect Jennifer Siegal used shipping containers in a custom home in downtown L.A., and architect Peter DeMaria designed a container-based home now under construction in Redondo Beach.

Jennifer Kretschmer, an architect based in San Jose who is designing her first shipping-container home for a client in Healdsburg, said that she hopes the designers who are interested in this form can come together and develop standards. "We are all in an experimental field," she said, "with each of us inventing the wheel on our own. It would be good to share our failures and successes."

If shipping containers are cheap, transportable and stackable and able to survive most disasters, why haven't they been more widely adopted already?

"Building codes -- that's really our big hurdle," said Kretschmer, adding that even though they are stronger than most construction forms, it's hard to convince planning departments of anything so new. Indeed, although some California counties have allowed shipping-container construction, Rancho Palos Verdes has proposed building codes that would disallow any shipping containers as housing.

As long as we are trading with Asia," explained Kretschmer, "there are going to be extra shipping containers, so in this sense it's a very green product. But I would never advocate using new shipping containers."

In this sense, shipping containers will never -- or at least should never-- be the ultimate building form. Steel is not a renewable resource, and moving it around is far from environmentally advisable. Ideally, our society won't overproduce these steel boxes forever. And even if it does, that overproduction won't be enough to satisfy our housing needs.

But shipping-container architecture does signal a new creativity among architects and builders that may be more powerful than any magic-bullet building technique. After a hundred years of environmentally disastrous construction methods and escalating real estate prices, the shipping container is more than a harebrained scheme of an eco-shelter movement -- it's a whisper of the weird world of housing to come.

Carol Lloyd is currently at work on a book about Bay Area real estate. She teaches a class on buying your first home in the Bay Area, and another class based on her best-selling career counseling book for creative people, "Creating a Life Worth Living." For more information, email her at surreal@sfgate.com.